Presentation Linkbase, Preferred Labels and Periods

Owned by Sebastiano Mussi
Last updated: Jul 19, 2023 by Paul Beckmann
4 min read

There is a common misconception that the Preferred Label Roles “PeriodStart” and “PeriodEnd” in XBRL are directly related to the displayed value from a fitting period. While some software vendors might have implemented their view in that way, you cannot automatically assume this to be true. Especially with ESEF, there has been a lot of confusion among auditors about this connection when using specific software.

“Presentation links are used to arrange taxonomy elements into a hierarchy and specific ordering. In general, different uses will require different sets of presentation links. There is one set of users - taxonomy developers and domain experts working with a taxonomy - whose presentation needs remain relevant throughout the entire lifecycle of a taxonomy. In some sense this view is "context free" as opposed to the presentation of instance data that is "context dependent." When taxonomies are published they cannot contain all possible presentations but they MAY contain at least one "developer's eye" view, which is "context free" in the sense that it does not need to take XBRL Instance contexts into account.”

https://www.xbrl.org/Specification/XBRL-2.1/REC-2003-12-31/XBRL-2.1-REC-2003-12-31+corrected-errata-2013-02-20.html#Hierarchy-in-a-presentation-linkbase

This is especially true when it comes to the usage of Preferred Labels. There is a more detailed section here.

“XBRL processors MAY use the value of the @preferredLabel attribute to choose between different labels that have been associated with the same concept. This can be particularly useful when a given concept is used in a variety of ways within a DTS. For example, cash can be used in the balance sheet and as the starting and ending balances in a cash flow statement. Each appearance of the concept in a set of presentation links MAY use this feature to indicate a different preferred label.”

https://www.xbrl.org/Specification/XBRL-2.1/REC-2003-12-31/XBRL-2.1-REC-2003-12-31+corrected-errata-2013-02-20.html#_5.2.4.2.1

Even is the Presentation Linkbase of your Entity-Specific Disclosure is correctly enriched, it is still “context free”. Just adding values from all the periods to the traditional tree-view might create the impression that values have been reported multiple times. Here is an example:

On the left side of the image, you can see the Presentation Linkbase with the PreferredLabelRoles. This must be considered as a standalone view and should reflect the structure of the report. On the right side of the image, we have simply added the numbers from the different periods. Since the technical element is independent of the PreferredLabelRole, each occurrence of the element also displays each value in each period. The LabelRole has no influence on the specified number or period. It exists ONLY for the representation of the label from the Presentation Linkbase structure.

Depending on how you try to make this representation different, it can of course look like there are duplicate entries. But even in our representation above, there are only three values, each displayed three times (for the same element). In XBRL, however, they are technically only present once.

If we look at how this can be disaggregated if the software makes wrong assumptions, it will look even more confusing.

The values from the screenshot above are displayed in the following way:

This presentation can be further disaggregated when taking the role/table and labelroles into account, thus displaying the actually tagged values:

If the software disregards which role/table the specific element belongs to, the presentation can get even more confusing:

These are the important take-aways from this:

  1. Make sure you understand how your software is building the representation, be it as a flat list, tree view or table, especially if you are an auditor! The assumptions that go into that representation may not be correct or fitting for your use case.

  2. There is a disconnect between Presentation Linkbase and PreferredLabelRoles on the one hand, and the reported values for a period and concept on the other hand. The representation of these varies according to the software used.

  3. The ESEF reporting manual requires "that issuers shall not report inconsistent duplicates" (Guidance 2.2.4 and http://www.xbrl.org/WGN/xbrl-duplicates/WGN-2015-12-09/xbrl-duplicates-WGN-2015-12-09.html ). This has to be validated by the filers. If the validation does not show a duplicate, there is none.